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	Sun, 18 Oct 2026 15:01:05 +0000
Date: Sun, 18 Oct 2026 16:01:04 +0100
From: Al Viro <viro@zeniv.linux.org.uk>
To: Christian Brauner <brauner@kernel.org>
Cc: linux-fsdevel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Chris Mason <mason@kernel.org>, Jan Kara <jack@suse.cz>,
	Jeff Layton <jlayton@kernel.org>, Aleksa Sarai <cyphar@cyphar.com>,
	Amir Goldstein <amir73il@gmail.com>, bpf@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH 02/17] namespace: check a submount for references right
 before unmounting it
Message-ID: <20261018150104.GG3535232@ZenIV>
References: <20260930-work-mount-fixes-3-v1-0-be34c83956ae@kernel.org>
 <20260930-work-mount-fixes-3-v1-2-be34c83956ae@kernel.org>
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Sender: Al Viro <viro@ftp.linux.org.uk>

On Wed, Sep 30, 2026 at 03:31:54PM +0200, Christian Brauner wrote:
>  static void shrink_submounts(struct mount *mnt)
>  {
> -	LIST_HEAD(graveyard);
> -	struct mount *m;
> -
> -	/* extract submounts of 'mountpoint' from the expiration list */
> -	while (select_submounts(mnt, &graveyard)) {
> -		while (!list_empty(&graveyard)) {
> -			m = list_first_entry(&graveyard, struct mount,
> -						mnt_expire);
> -			touch_mnt_namespace(m->mnt_ns);
> -			umount_tree(m, UMOUNT_PROPAGATE|UMOUNT_SYNC);
> -		}
> +	for (;;) {
> +		if (!__shrink_submounts(mnt))
> +			break;

Everything else aside...  Why would one ever use

	for (;;) {
		if (!test())
			break;
	}

instead of

	while (test())
		;

outside of IOCCC?  Sure, compiler will generate the same code, but...